The oncolytic adenovirus VCN01 promotes anti tumor effect in primitive neuroectodermal tumor models

Last advances in the treatment of pediatric tumors has led to an increase of survival rates of children affected by primitive neuroectodermal tumors, however, still a significant amount of the patients do not overcome the disease. In addition, the survivors might suffer from severe side effects caused by the current standard treatments. Oncolytic virotherapy has emerged in the last years as a promising alternative for the treatment of solid tumors. In this work, we study the anti-tumor effect mediated by the oncolytic adenovirus VCN-01 in CNS-PNET models. VCN-01 is able to infect and replicate in PNET cell cultures, leading to a cytotoxicity and immunogenic cell death. In vivo, VCN-01 increased significantly the median survival of mice and led to long-term survivors in two orthotopic models of PNETs. In summary, these results underscore the therapeutic effect of VCN-01 for rare pediatric cancers such as PNETs, and warrants further exploration on the use of this virus to treat them

Minimal RB-responsive E1A Promoter Modification to Attain Potency, Selectivity, and Transgene-arming Capacity in Oncolytic Adenoviruses

Oncolytic adenoviruses are promising anticancer agents due to their ability to self-amplify at the tumor mass. However, tumor stroma imposes barriers difficult to overcome by these agents. Transgene expression is a valuable strategy to counteract these limitations and to enhance antitumor activity. For this purpose, the genetic backbone in which the transgene is inserted should be optimized to render transgene expression compatible with the adenovirus replication cycle and to keep genome size within the encapsidation size limit. In order to design a potent and selective oncolytic adenovirus that keeps intact all the viral functions with minimal increase in genome size, we inserted palindromic E2F-binding sites into the endogenous E1A promoter. The insertion of these sites controlling E1A-Δ24 results in a low systemic toxicity profile in mice. Importantly, the E2F-binding sites also increased the cytotoxicity and the systemic antitumor activity relative to wild-type adenovirus in all cancer models tested. The low toxicity and the increased potency results in improved antitumor efficacy after systemic injection and increased survival of mice carrying tumors. Furthermore, the constrained genome size of this backbone allows an efficient and potent expression of transgenes, indicating that this virus holds promise for overcoming the limitations of oncolytic adenoviral therapy

Characterization of the Antiglioma Effect of the Oncolytic Adenovirus VCN-01.

Despite the recent advances in the development of antitumor therapies, the prognosis for patients with malignant gliomas remains dismal. Therapy with tumor-selective viruses is emerging as a treatment option for this devastating disease. In this study we characterize the anti-glioma effect of VCN-01, an improved hyaluronidase-armed pRB-pathway-selective oncolytic adenovirus that has proven safe and effective in the treatment of several solid tumors. VCN-01 displayed a significant cytotoxic effect on glioma cells in vitro. In vivo, in two different orthotopic glioma models, a single intra-tumoral administration of VCN-01 increased overall survival significantly and led to long-term survivors free of disease

Correction: Characterization of the Antiglioma Effect of the Oncolytic Adenovirus VCN-01.

[This corrects the article DOI: 10.1371/journal.pone.0147211.]

The oncolytic adenovirus VCN01 promotes anti tumor effect in primitive neuroectodermal tumor models

Last advances in the treatment of pediatric tumors has led to an increase of survival rates of children affected by primitive neuroectodermal tumors, however, still a significant amount of the patients do not overcome the disease. In addition, the survivors might suffer from severe side effects caused by the current standard treatments. Oncolytic virotherapy has emerged in the last years as a promising alternative for the treatment of solid tumors. In this work, we study the anti-tumor effect mediated by the oncolytic adenovirus VCN-01 in CNS-PNET models. VCN-01 is able to infect and replicate in PNET cell cultures, leading to a cytotoxicity and immunogenic cell death. In vivo, VCN-01 increased significantly the median survival of mice and led to long-term survivors in two orthotopic models of PNETs. In summary, these results underscore the therapeutic effect of VCN-01 for rare pediatric cancers such as PNETs, and warrants further exploration on the use of this virus to treat them

VCN-01 disrupts pancreatic cancer stroma and exerts antitumor effects

Background Pancreatic ductal adenocarcinoma (PDAC) is characterized by dense desmoplastic stroma that limits the delivery of anticancer agents. VCN-01 is an oncolytic adenovirus designed to replicate in cancer cells with a dysfunctional RB1 pathway and express hyaluronidase. Here, we evaluated the mechanism of action of VCN-01 in preclinical models and in patients with pancreatic cancer. Methods VCN-01 replication and antitumor efficacy were evaluated alone and in combination with standard chemotherapy in immunodeficient and immunocompetent preclinical models using intravenous or intratumoral administration. Hyaluronidase activity was evaluated by histochemical staining and by measuring drug delivery into tumors. In a proof-of-concept clinical trial, VCN-01 was administered intratumorally to patients with PDAC at doses up to 1x10(11) viral particles in combination with chemotherapy. Hyaluronidase expression was measured in serum by an ELISA and its activity within tumors by endoscopic ultrasound elastography. Results VCN-01 replicated in PDAC models and exerted antitumor effects which were improved when combined with chemotherapy. Hyaluronidase expression by VCN-01 degraded tumor stroma and facilitated delivery of a variety of therapeutic agents such as chemotherapy and therapeutic antibodies. Clinically, treatment was generally well-tolerated and resulted in disease stabilization of injected lesions. VCN-01 was detected in blood as secondary peaks and in post-treatment tumor biopsies, indicating virus replication. Patients had increasing levels of hyaluronidase in sera over time and decreased tumor stiffness, suggesting stromal disruption. Conclusions VCN-01 is an oncolytic adenovirus with direct antitumor effects and stromal disruption capabilities, representing a new therapeutic agent for cancers with dense stroma

VCN-01 treatment results in a significant antitumor effect in two different <i>in vivo</i> glioma models.

<p>(A) Kaplan-Meier survival curves for overall survival in VCN-01 (10⁷ pfu), VCN (10⁸ pfu) and control (PBS)-treated athymic mice bearing U87 MG and GSC23 intracranial xenografts. Intracranial implantation of U87 MG or GSC23 cells (day 0) was followed by one intratumoral injection (on day 3) of VCN-01 (10⁷ pfu; <i>n</i> = 10), VCN-01 (10⁸ pfu; <i>n</i> = 10), VCN-01 10⁸ pfu UV inactivated (VCN01-UVi; <i>n</i> = 10) or PBS (<i>control</i>; <i>n</i> = 10). The <i>P</i> values were determined by the log-rank test and represent a comparison of survival of VCN-01–treated mice with that of mice treated with PBS. (B) Hematoxilin and eosin staining of cross sections of U87 MG or GSC23 xenografts treated with PBS or VCN-01. (C) Hexon immunostaining of the brains of animals treated with VCN-01 (10⁷ pfu), VCN (10⁸ pfu) or control (PBS). The tissue sections were incubated with anti-hexon antibodies. The magnification of histo-chemical images is ×20. (D) Representative Hyaluronic acid and hexon immunostaining of the brains of animals bearing GSC23 cell line treated with VCN-01 (10⁷ pfu), or control (PBS). The tissue sections were incubated with anti-hyaluronic acid and hexon antibodies. The magnification of histo-chemical images is ×20.</p

VCN-01 replicates efficiently in glioma cell lines <i>in vitro</i>.

<p>(A) The expression amounts of Fiber and E1A proteins in human glioblastoma were determined by Western blot analysis. Note that the levels were viral dose-dependent in all the cell lines. (B) The expression of Fiber and PH20 mRNA in all the cell lines were determined by real time PCR; expression of both genes was correlated, suggesting similar kinetics and dose-dependency. The cell lines used were SNB19, T98G, U87 MG, A172, U373 MG, U251 MG, GSC23 and GSC11. (C) The quantification of VCN-01 viral replication in all the cell lines. Human glioblastoma cells were infected with two dilutions of VCN-01 (1 MOI and 10 MOIs). The virus replicated up to ten-times better in the cells infected with 10 MOIs, which demonstrates that the virus infected and replicated efficiently in glioblastoma cell lines <i>in vitro</i>. (D) The quantification of VCN-01 viral replication in GL261 murine cell line. GL261 cells were infected with two dilutions of VCN-01 (100 MOI and 300 MOIs). As a control for the replication we used cells infected with VCN-01 at 300 MOIs and collected 4 hours after infection, during this time the virus does not have time to replicate indicating the initial viral particles.</p